'04 Venture - Hard Shifting - FIXED (Interesting)

[bleepster]

we are heading to Flordia April 1st for 10 days. Driving the '04 venture (106,000 miles). for the past 4-5 months its been shifting hard when hot.
for the past year - my Check Engine Light was on - and i had the codes read and Autozone told me it was my upstream O2 sensor........

To get the van ready for the trip, I did the following:

All new tires
New Air Filter
new Fuel Filter
New PCV Valve
New Shocks (Rear)

took the van to a close friend who works at Advance Auto and he read the codes as well. It was a bad MAF Sensor. he said that could also give a false reading on the upstream O2 sensor. we replaced the MAF Sensor, and air filter and other items listed above. he cleared out the codes, and for the past 2 weeks everything has been great. THE HARD SHIFTING HAS DISSAPPEARED AS WELL.

I will admit, my air filter was DIRTY, actually I was ashamed of it.
My buddy suspects I was starving the engine of air, and that was resulting in the hard shifting.

is that an accurate statement? weather has been warmer here in michigan, and it hasnt shifted hard since we did all the work.

any thoughts or ideas?

[paprius4030]

Makes sense!

[dewaynep]

A bad MAF sensor won't necesarily give a "false" O2 reading, but it can cause the computer to think that it is a bad reading. In other words, the O2 sensor was reading just fine but the computer was thinking the values should be different, that's why you got the CEL. This is why it is of the utmost importance to not just read the code and change a part, but rather, read the code and interpret the cause. If you had gone to "the Zone" and didn't have a friend working there you would have walked away with a new O2 sensor instead of the correct part. It all may have been caused by the dirty air filter and a dirty maf.